It should, I have a 5yr old 64bit PC with the Radeon 5750 card and just finished playing Horizon for first time. I played for around 3hrs just doing my usual stuff. Never tried to land on a planet or kit out with an SRV or that. I did notice quite a bit of difference with it though. I would say that everything is much better in 64bit. I never changed anything in the Options just had a look to see what was there and left it at the default settings. Like the OP I wondered if my PC would not be enough for Horizons but I think it is actually better than before when it had the 32bit version of E
. I ran Speccy just before signing out and the Graphic card was at 50 degrees which is well cool so it isn't being overworked. Perhaps that will change when I try planetary landing, using SRV etc but at the moment I am happy with my PC's performance. Screen shot of my PC's particulars via Speccy below.
